“These are very toxic air pollutants,” said Owens. “The substantial penalty reflects the seriousness of the violations.”

The settlement results from violations of state and federal regulations governing emission of hazardous air pollutants, failure to submit test reports from the company's manufacturing plant, failure to install required temperature monitors by the required regulatory deadline and failure to submit required compliance certification reports. ADEQ issued seven notices of violation to the company in 2003-2004 for not following the law.

Take steps to assess raw materials used in the manufacturing process to ensure no future violations of air pollutant limits.

Improve air quality in the neighboring community of Rillito by applying dust suppressants to an unpaved community road, installing a heating, cooling, ventilation system and air purifiers in a Rillito Community Center, and offering air purifiers to local Rillito residents.

Arizona Portland Cement, a division of California Portland Cement Company, makes cement in Rillito, Ariz., just west of Tucson. The settlement is subject to court approval.